Field of the Invention
The present invention relates to a magnetic tape.
Discussion of the Background
Magnetic recording media include tape-shaped media and disk-shaped media. Magnetic recording media in the form of tapes, that is, magnetic tapes, are primarily employed in storage applications such as data-backup tapes.
To record and reproduce signals on a magnetic tape, the magnetic tape is normally run within a drive, and the tape surface (the surface of the magnetic layer) and a magnetic head are brought into contact (slide).
In the recording and reproduction, a portion of the surface of the magnetic layer may be shaved off by repeated running in which the surface of the magnetic layer slides against the head. This may produce foreign matter that sometimes adheres to the head. With repeated running (also referred to hereinafter simply as “running”) of the magnetic tape in a state where foreign matter has adhered to the head in this manner, the distance between the magnetic tape and the head is affected by the foreign matter and the output sometimes ends up fluctuating (spacing loss). Such spacing loss may compromise electromagnetic characteristics with repeated running. Abrasives have been incorporated into the magnetic layer to impart to the surface of the magnetic layer a function of removing foreign matter that has adhered to the head as a countermeasure to such adhesion (for example, see Japanese Unexamined Patent Publication (KOKAI) No. 2014-179149 or English language family member US2014/272474A1 and Japanese Unexamined Patent Publication (KOKAI) No. 2005-243162, which are expressly incorporated herein by reference in their entirety). Hereinafter, the function of the surface of the magnetic layer removing foreign matter that has adhered to the head will be referred to as the “abrasiveness of the surface of the magnetic layer,” or simply as “abrasiveness.”
Due to increases in the amount of information being recorded, ever higher density recording is being demanded in the area of magnetic recording. To achieve this higher density recording, methods of reducing the size of the particles in the magnetic powder employed in the magnetic layer and increasing the fill rate of the magnetic layer have conventionally been investigated. In this regard, among the various ferromagnetic powders, the fact that ferromagnetic hexagonal ferrite powder is suited to achieving higher density recording through a reduction in particle size is known (for example, see Japanese Unexamined Patent Publication (KOKAI) No. 2012-203955 or English language family members US2012/243120A1 and U.S. Pat. No. 8,681,451, which are expressly incorporated herein by reference in their entirety).